Put.com published in a recent article about twin turbo V6 engines that Ford confirmed that the Ecoboost does in fact gain more power with premium fuel in stock form. The Ecoboost gains another 20hp and 10lb+ft of torque on premium fuel.

"We should note Ford tells us that its power outputs improve slightly, measuring 385 horsepower and 430 pounds-feet of torque when using premium fuel, instead of the regular fuel the owner's manual recommends."

Put.com published in a recent article about twin turbo V6 engines that Ford confirmed that the Ecoboost does in fact gain more power with premium fuel in stock form. The Ecoboost gains another 20hp and 10lb+ft of torque on premium fuel.

"We should note Ford tells us that its power outputs improve slightly, measuring 385 horsepower and 430 pounds-feet of torque when using premium fuel, instead of the regular fuel the owner's manual recommends."

I've always speculated that Ford runs an adaptive tune on the eb like it does the 5.0. The manual never recommends a particular octane iirc. But it does advise owners to run premium fuel when towing at higher altitudes for better performance. I just wasn't sure If it was for protection from detonation or indeed better performance. Only problem is that premium in higher elevated areas seems to be only 90 octane.